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  • Writer's pictureACT Wessex Animal Health

Osmolarity & Homogenization in Calf Milk Powders

Have you ever wondered what is meant by the terms “Osmolarity” and “Homogenization” with regards to Calf Milk Replacers.

Osmolarity relates to the process of osmosis. A calf’s blood has an osmolarity of approx. 300 and cow’s milk 300-320 so the two are therefore well balanced and little transfer of water from blood to gut would occur. The main factors affecting osmolality are Lactose levels i.e. sugar molecules and salt (Sodium and chloride ions). Whey based milk replacers will generally have a higher lactose and salt level and therefore higher osmolarity. Though in better quality whey products one can use whey powder low in lactose in order to lower osmolarity.

Calf milks with high skim content for Example Sure Start, Calf Gold, Calf Distinction, Calf Enterprise, Calf Supreme and also Calf Prime and Calf Delight have always had a lower osmolarity.

It is wrong for some manufacturers to infer that their calf milk is the only calf milk with low osmolarity compared to others on the market.

This osmolarity is nothing new and we have always been aware of the difference between high quality skim products in comparison to some poorer quality whey products in terms of looser dung occurring when poorer whey products are fed.

To clarify the process of homogenisation – this is when liquid fats/oils are mixed with skim and homogenised to create fat molecules of less than 2 microns in diameter which are then encapsulated in milk solids and spray dried at low temperature. This process results in less free fat in calf milk and leads to greater digestibility.

There are other cheaper processes when making Fat Filled Bases, they often lead to larger fat molecules and poorer encapsulation. The result is more free fat in the calf milk leading to poor digestibility.

The reality is some are trying to re-invent the wheel in relation to osmolarity/homogenisation. The move to higher fat/lower protein milk powders with similar ratios to cow’s milk (Fat 3.8-4.0% and Protein 3.1-3.3%) %) does have some merit.

This is particularly so with many large herds where calf sheds can be very cold with calves needing additional energy during the critical first 4-week period of its life.

We now have 2 products, Calf Distinction and Calf Enterprise Once-a-Day with this reverse ratio of more fat and less protein, both with a high SKIM content with 100% all milk protein.

All Britmilk Calf Milk Powders have a comprehensive package of health promoting ingredients derived from Yoghurt and Colostrum Cultures, Yeast derivatives, Essential Oils, Plant extracts and Organic Acids all included to promote health and performance in young calves.



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